Use Cases and Scenarios for Business Analysts
Use Cases and Scenarios: Mapping Interactions and Outcomes
Description
What is a Use Case?
A use case describes the interactions between:
- The primary actor (who has the goal),
- The solution (the system being developed),
- And any secondary actors (who assist in achieving the goal).
Use cases are usually triggered by the primary actor, but in some methods, they might also be triggered by:
- Another system
- An external event
- A timer
Purpose of a Use Case:
A use case details the possible outcomes of an actor’s attempt to achieve a goal.
It maps out:
- The primary (basic) flow — the most direct and successful way to achieve the goal.
- Alternative flows — paths taken if variations occur.
- Exception flows — paths when errors or failures prevent the goal.
✅ Use cases are always written from the actor’s point of view, not describing the internal system workings.
What is a Use Case Diagram?
A use case diagram is a graphical representation showing:
- Actors
- Their associated use cases
- The relationships between them
It visually highlights what the system must do without specifying how.
Types of Use Cases:
- Business Use Cases: Describe business processes or organizational activities (at a higher level).
- System Use Cases: Describe interactions between an actor and a software system (technical level).
What is a Scenario?
A scenario is one specific path through a use case.
It represents a series of steps performed by:
- Actors
- Or the solution
to achieve the goal in a particular situation.
➔ A single use case includes multiple scenarios (e.g., successful scenario, failure scenario, alternate paths).
Summary Table
| Concept | Definition |
|---|---|
| Use Case | Describes all possible ways to achieve an actor’s goal through the system. |
| Primary Flow | The main, successful path to achieve the goal. |
| Alternative Flow | A variation in steps leading to the goal. |
| Exception Flow | An error or interruption that prevents goal achievement. |
| Scenario | One specific instance/path through a use case. |
| Use Case Diagram | A visual overview of actors, use cases, and their relationships. |
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